The present invention relates to apparatus for connecting rod-shaped articles end-to-end, especially for connecting filter plugs or mouthpieces with plain cigarettes, cigarillos or cigars. More particularly, the invention relates to improvements in apparatus for convoluting adhesive-coated uniting bands around groups of coaxial rod-shaped articles which constitute or form part of smoker's products. Still more particularly, the invention relates to improvements in apparatus of the type wherein adhesive-coated uniting bands are draped around groups of coaxial rod-shaped articles while the articles move sideways through a gap whose width is less than the diameter of a group so that the groups of articles are caused to roll about their respective axes.
It is well known to equip a filter tipping machine with an apparatus which connects filter plugs or mouthpieces with plain cigarettes to form filter cigarettes of unit length or double unit length. Such apparatus normally comprise a first rolling device which is a rotary drum-shaped conveyor, and a second rolling device which is a stationary block or an endless belt. Reference may be had, for example, to commonly owned U.S. Pat. Nos. 3,483,873 and 3,527,234 respectively granted on Dec. 16, 1969 and Sept. 8, 1970 to Alfred Hinzmann. Groups of coaxial filter plugs and plain cigarettes are delivered onto the first rolling device which transports successive groups through a relatively narrow gap between the two rolling devices so that the groups are compelled to rotate about their respective axes. Adhesive-coated uniting bands are attached to successive groups prior to entry into the gap, and the uniting bands are converted into tubes which surround the filter plugs and the adjacent portions of the plain cigarettes as a result of rotation of the groups about their axes. In earlier versions of such apparatus, the first rolling device (conveyor) has several ribs which are parallel to its axis and extend outwardly beyond its peripheral surface. The ribs flank convex fields along which the groups of coaxial articles roll backwards during travel through the aforementioned gap. An advantage of the ribs is that they determine, in advance, the extent of rotation of each group about its axis. In other words, the ribs insure that each group rotates to an extent which suffices to insure satisfactory convolution of uniting bands around the filter plugs and around the adjacent portions of plain cigarettes. When a group emerges from the gap, it lies against one of the ribs and is thereby held in a predetermined position which facilitates its transfer onto the next conveyor, e.g., onto a conveyor whereon the group of united articles is severed midway between its ends to yield two filter cigarettes of unit length. The procedure is quite similar to the manufacture of certain types of filter tipped cigarillos and cigars.
An advantage of the just described earlier apparatus is that their operation is not unduly affected by deposits of adhesive paste on the first and/or second rolling device. In fact, the just described apparatus with ribs at the periphery of the first rolling device produce a certain amount of self-cleaning action so that the intervals of stoppage for the purpose of removing accumulations of adhesive paste are infrequent. Some adhesive is likely to deposit on the surfaces of the two rolling devices because one side of each uniting band is coated with adhesive and the surplus of adhesive is likely to escape beyond the axial ends of the convoluted uniting band during transport of the respective group through the gap between the two rolling devices. Also, some of the surplus of adhesive paste can escape from the seam where the marginal portions of the convoluted uniting band overlap each other.
Recent types of filter tipping machines for the production of filter cigarettes or the like are equipped with modified convoluting apparatus whose versatility exceeds that of the apparatus using a first rolling device which is a conveyor with peripheral ribs. The ribs are spaced apart from each other (as considered in the circumferential direction of the first rolling device) to such an extent that a group which is transferred onto the conveyor and has a given diameter can complete one full revolution about its own axis before it moves into abutment with and is arrested (against further rotation about its axis) by the nearest rib. Thus, if the manufacturer wishes to produce filter cigarettes having larger or smaller diameters, the first rolling device must be replaced with a different rolling device wherein the spacing between neighboring ribs conforms to the diameters of the filter cigarettes to be produced. The aforementioned recent types of convoluting apparatus utilize first rolling devices which constitute or include rotary drum-shaped conveyors with relatively shallow axially parallel peripheral flutes for portions of groups of coaxial rod-shaped articles. The width of the gap between the two rolling devices is such that a group which has entered a shallow flute continues to roll about its own axis and moves out of and beyond the flute. in other words, such apparatus allow for conversion of uniting bands into tubes while the respective groups of coaxial rod-shaped articles complete more than one revolution (e.g., two or three full revolutions) about their respective axes. This enhances the sealing action of convoluted uniting bands and insures that each converted uniting band forms a tube which is a true cylinder of eye-pleasing appearance. Such eye-pleasing appearance and/or airtight connection of filter plugs to neighboring coaxial plain cigarettes is not always insured if the groups are allowed to complete only one revolution about their axes during travel through the aforementioned gap between the two rolling devices. In most instances, a group which is admitted into the gap enters and leaves at least one but normally two shallow grooves before it advances through and beyond the gap.
The just described recent types of convoluting apparatus exhibit a drawback which leads or can lead to frequent interruptions of operation of a filter tipping machine, namely, the surfaces of the two rolling devices are likely to be contaminated by adhesive which is squeezed beyond the marginal portions of uniting bands during their conversion into tubes. This is due to the fact that each group completes several revolutions about its axis during travel through the gap between the two rolling devices. Adhesive paste which accumulates on the first and/or second rolling device is likely to interfere with proper transfer of groups onto the first rolling device, with proper positioning of groups on the first rolling device, with removal of groups from the first rolling device downstream of the gap, and/or with entry of groups into the inlet of the gap. Moreover, adhesive paste which accumulates on the surfaces of the two rolling devices is likely to contaminate the finished products so that the contaminated products must be segregated from satisfactory products. Frequent interruptions of the operation of a modern filter tipping machine are highly undesirable because such machines turn out several thousand filter cigarettes per minute so that losses in output which are attributable to a single stoppage of the filter tipping machine on account of undue accumulation of adhesive on the one and/or the other rolling device can run into tens and hundreds of thousands.
German Pat. No. 823,276 to Korber et al. discloses a machine for the manufacture of filter cigarettes wherein the uniting bands are replaced by sleeves made of hardenable plastic material which is sprayed onto the regions where plain cigarettes abut against filter plugs. Plastic material which deposits on the conveyor means for transport of filter plugs in register with plain cigarettes is caused to pass through a bath which contains a suitable solvent. The action of solvent can be assisted by a brush which is installed in the vessel for the liquid bath. A drawback of such proposal is that the solvent is likely to affect the taste of finished products and also that the conveyor means cannot be driven at a high speed because it must allow for evaporation of solvent before the respective flutes or cradles of the conveyor means receive fresh rod-shaped articles. Furthermore, the wear upon the brush is very pronounced because its bristles are in permanent contact with the moving conveyor means.
U.S. Pat. No. 3,036,581 to Dearsley discloses a cigarette maker wherein a so-called kicker plate carries a bracket for a brush and a finger. The finger and the brush are caused to move through a pair of adjacent spaced nests of rollers on a drum to expel any cigarettes or plug or tobacco material that might have remained in the nested roller holders. The purpose of the brush and/or finger is to expel the constituents of final products, not to scrape off adhesive which accumulates on certain parts owing to the application of excessive amounts of adhesive to uniting bands for cigarettes and filter plugs or like groups of coaxial rod-shaped articles. Moreover, the brush and the finger are in constant use so that they are subjected to extensive wear and must be inspected and replaced at frequent intervals.
U.S. Pat. No. 3,077,889 to Patterson discloses a filter tipping machine wherein deposits of adhesive on a second rolling device cooperating with a first rolling device or conveyor are removed by brushes which are secured to the conveyor and orbit abut the axis of the conveyor while the filter tipping machine is in use. The second rolling device is much longer than necessary and is reciprocated in parallelism with the axis of the conveyor so that it is continuously cleaned by the brushes. Such proposal is satisfactory insofar as the cleaning action upon the concave surface of the second rolling device is concerned. However, the complementary surface of the conveyor is not cleaned at all. Also, the wear upon the brushes is very pronounced because the brushes are used whenever the filter tipping machine is on. Furthermore, movements of the second rolling device in parallelism with the axis of the rolling conveyor while the filter tipping machine is in actual use are likely to affect the accuracy with which the uniting bands are convoluted around plain cigarettes and adjoining filter plugs. The mechanism for reciprocating the second rolling device is complex and expensive.